The present invention relates to energy absorber constructions, and more particularly relates to an energy absorber construction with aligned crush lobes expandable in opposite directions for increased crush stroke and that can be customized for stepped energy absorption. The present inventive concepts are useful in vehicles for passenger safety and for pedestrian safety, but are not limited to only those areas.
Energy absorption is important in vehicles for occupant safety in the event of a vehicle crash. Energy absorption occurs in components that provide a combination of optimal crush resistance and impact stroke, with the crush resistance avoiding spikes while providing optimal maximum energy absorption, and the impact stroke being sufficiently long to allow energy absorption without itself providing injury to the vehicle occupant or impacted pedestrian. However, there are conflicting requirements. For example, components providing an increased impact stroke length also tend to take away from passenger space in a vehicle's passenger compartment, which space is already at a premium due to downsized vehicles. Also, increased vehicle weight due to added components can be problematic.
Aside from conflicting requirements related to crush stroke lengths, it is important to control crush resistance over the impact stroke. Some less severe crashes require minimal crush resistance and/or minimal crush stroke, while more severe vehicle crashes require maximum crush resistance and preferably longer crush stroke lengths. Further, sometimes it is desirable to incorporate stepped increases in crush resistance over a given crush stroke, so that one component arrangement can provide different optimized energy absorption for different crash scenarios. Further, it is desirable to provide the energy absorber as an assembled unit, minimizing total cost while using few components. This allows one to maximize vehicle value by minimizing component cost and assembly time yet while maximizing function(s) and aesthetics of the overall vehicle. All of this must preferably be done cost-effectively, efficiently, and must not result in overly complex or expensive parts and components.
Notably, many energy absorber constructions are not easy to modify to fit particular package spaces, nor to allow particular mounting situations, nor to provide particular stepped energy absorption, nor to provide customizable crush strokes. An energy absorber construction is desired that provides flexibility of design and shape and mounting, while also taking up a minimum of space, using few components, and yet meets all functional requirements, including operation at high and low temperatures.
In addition to vehicle passenger safety, modern vehicles are being designed for improved pedestrian safety. For example, when a collision with a pedestrian occurs, the pedestrian often falls onto the vehicle's hood, with the pedestrian's head striking a rear of the hood and/or the vehicle's front windshield. This can cause a concussion and/or other head injury. The resulting head injury can potentially be reduced by “softening” the head impact. One alternative is to lift a rear of the hood in a severe pedestrian impact prior to engagement in order to cushion engagement of the head against vehicle components. However, there are many functional and aesthetic requirements of a hood, especially near the vehicle's front windshield, including appearance, control of engine noise, control of air flow and/or water flow, occupant safety issues (i.e., from the hood being driven toward the windshield), and coordination with placement and shape of any safety device with the vehicle's cowl and other vehicle components such as vehicle windshield wipers. Thus, the task of reducing head impact is not easily done.